// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_LOCATION_H_
#define BASE_LOCATION_H_

#include <stddef.h>

#include <cassert>
#include <string>

#include "base/base_export.h"
#include "base/hash.h"

namespace tracked_objects {

// Location provides basic info where of an object was constructed, or was
// significantly brought to life.
class BASE_EXPORT Location {
public:
    // Constructor should be called with a long-lived char*, such as __FILE__.
    // It assumes the provided value will persist as a global constant, and it
    // will not make a copy of it.
    Location(const char* function_name,
        const char* file_name,
        int line_number,
        const void* program_counter);

    // Provide a default constructor for easy of debugging.
    Location();

    // Copy constructor.
    Location(const Location& other);

    // Comparator for hash map insertion.
    // No need to use |function_name_| since the other two fields uniquely
    // identify this location.
    bool operator==(const Location& other) const
    {
        return line_number_ == other.line_number_ && file_name_ == other.file_name_;
    }

    const char* function_name() const { return function_name_; }
    const char* file_name() const { return file_name_; }
    int line_number() const { return line_number_; }
    const void* program_counter() const { return program_counter_; }

    std::string ToString() const;

    // Hash operator for hash maps.
    struct Hash {
        size_t operator()(const Location& location) const
        {
            // Compute the hash value using file name pointer and line number.
            // No need to use |function_name_| since the other two fields uniquely
            // identify this location.

            // The file name will always be uniquely identified by its pointer since
            // it comes from __FILE__, so no need to check the contents of the string.
            // See the definition of FROM_HERE in location.h, and how it is used
            // elsewhere.
            return base::HashInts(reinterpret_cast<uintptr_t>(location.file_name()),
                location.line_number());
        }
    };

    // Translate the some of the state in this instance into a human readable
    // string with HTML characters in the function names escaped, and append that
    // string to |output|.  Inclusion of the file_name_ and function_name_ are
    // optional, and controlled by the boolean arguments.
    void Write(bool display_filename, bool display_function_name,
        std::string* output) const;

    // Write function_name_ in HTML with '<' and '>' properly encoded.
    void WriteFunctionName(std::string* output) const;

private:
    const char* function_name_;
    const char* file_name_;
    int line_number_;
    const void* program_counter_;
};

// A "snapshotted" representation of the Location class that can safely be
// passed across process boundaries.
struct BASE_EXPORT LocationSnapshot {
    // The default constructor is exposed to support the IPC serialization macros.
    LocationSnapshot();
    explicit LocationSnapshot(const tracked_objects::Location& location);
    ~LocationSnapshot();

    std::string file_name;
    std::string function_name;
    int line_number;
};

BASE_EXPORT const void* GetProgramCounter();

// Define a macro to record the current source location.
#define FROM_HERE FROM_HERE_WITH_EXPLICIT_FUNCTION(__func__)

#define FROM_HERE_WITH_EXPLICIT_FUNCTION(function_name) \
    ::tracked_objects::Location(function_name,          \
        __FILE__,                                       \
        __LINE__,                                       \
        ::tracked_objects::GetProgramCounter())

} // namespace tracked_objects

#endif // BASE_LOCATION_H_
